In my prior U.S. Pat. No. 3,923,247 issued Dec. 2, 1975--Jeffrey A. White, I disclosed a snow-making device employing a typical gun component with a unique nozzle and restricter design. In this prior art construction, a nozzle design for subjecting the non-compressable medium, water, and the compressable medium, air, to a two-stage acceleration experienced at the downstream or horn portion of the nozzle was disclosed. The restricter was made adjustable inwardly and outwardly of the nozzle so as to vary the annular gap between the restricter and nozzle in order to effectively tune the snow-making device for maximum artificial snow production at a given temperature.
In practicing the invention of my prior patent, I have observed that adjusting the restricter inwardly results in a reduction in the two phase flow and additionally, the size of the snow particles produced. Given the relatively small size to weight ratio of these particles, they tend to rise or be blown away from the site intended to be covered with the artificial snow produced by the nozzle. In a like manner, I have also found that a large gap results in an increase in air supply necessary for proper snow production. Where the gap is too large, the nozzle takes on the characteristics of an unrestricted nozzle and its attendant efficiency loss.
One characteristic common to all snow-making equipment is that they are relatively inefficient when producing snow in situations where the device is operating at an ambient temperature of 15.degree.-20.degree. F. and upwards. In this operating range, evaporation of the water particles in the air-water mix is the dominant form of heat removal necessary in order to have the particles freeze. Higher air-to-water ratios are required in this range with an attendant increase in exit velocities from the nozzle. This is because the temperature gradient between the water and the ambient air (.DELTA.t) is relatively small. At lower operating ambient temperatures, .DELTA.t increases and convection and conduction become the predominant factors in cooling (freezing) the water particles exiting from the nozzle. In this lower ambient temperature range, the ratio of air-to-water can therefore be reduced with a corresponding reduction in exit velocities.